Computing devices such as personal computers, servers and network devices are the backbone of information technology systems. The increased density of computing devices (e.g., in a computer cluster) consumes more power and generates more heat. Thus, thermal management becomes critical for maintaining reliability of the computing devices.
Cooling fans have been used to lower a computing device's internal temperature by exhausting hot air from its chassis. Compared with other cooling methods such as liquid cooling, cooling fans are effective and easy to maintain. However, an effective control of the cooling fan speed is required to keep the internal temperature of a computing device within a preferred range. For example, an insufficiently low fan speed results in poor air circulation and overheating of the computing device; conversely, an unnecessarily high fan speed causes overcooling of the device and a waste of energy.